1,636 research outputs found
Multiple paternity in superfetatious live-bearing fishes.
Superfetation, the ability to carry several overlapping broods at different developmental stages, has evolved independently multiple times within the live-bearing fish family Poeciliidae. Even though superfetation is widespread among poeciliids, its evolutionary advantages remain unclear. Theory predicts that superfetation should increase polyandry by increasing the probability that temporally overlapping broods are fertilized by different fathers. Here, we test this key prediction in two poeciliid species that each carry two temporally overlapping broods: Poeciliopsis retropinna and P. turrubarensis. We collected 25 females per species from freshwater streams in South-Eastern Costa Rica and assessed multiple paternity by genotyping all their embryos (420 embryos for P. retropinna; 788 embryos for P. turrubarensis) using existing and newly developed microsatellite markers. We observed a high frequency of unique sires in the simultaneous, temporally overlapping broods in P. retropinna (in 56% of the pregnant females) and P. turrubarensis (79%). We found that the mean number of sires within females was higher than the number of sires within the separate broods (2.92 sires within mothers vs. 2.36 within separate broods in P. retropinna; and 3.40 vs 2.56 in P. turrubarensis). We further observed that there were significant differences in the proportion of offspring sired by each male in 42% of pregnant female P. retropinna and 65% of female P. turrubarensis; however, this significance applied to only 9% and 46% of the individual broods in P. retropinna and P. turrubarensis, respectively, suggesting that the unequal reproductive success of sires (i.e. reproductive skew) mostly originated from differences in paternal contribution between, rather than within broods. Together, these findings tentatively suggest that superfetation may promote polyandry and reproductive skew in live-bearing fishes
On the complexity of color-avoiding site and bond percolation
The mathematical analysis of robustness and error-tolerance of complex
networks has been in the center of research interest. On the other hand, little
work has been done when the attack-tolerance of the vertices or edges are not
independent but certain classes of vertices or edges share a mutual
vulnerability. In this study, we consider a graph and we assign colors to the
vertices or edges, where the color-classes correspond to the shared
vulnerabilities. An important problem is to find robustly connected vertex
sets: nodes that remain connected to each other by paths providing any type of
error (i.e. erasing any vertices or edges of the given color). This is also
known as color-avoiding percolation. In this paper, we study various possible
modeling approaches of shared vulnerabilities, we analyze the computational
complexity of finding the robustly (color-avoiding) connected components. We
find that the presented approaches differ significantly regarding their
complexity.Comment: 14 page
Phase diagram for non-axisymmetric plasma balls
Plasma balls and rings emerge as fluid holographic duals of black holes and
black rings in the hydrodynamic/gravity correspondence for the Scherk-Schwarz
AdS system. Recently, plasma balls spinning above a critical rotation were
found to be unstable against m-lobed perturbations. In the phase diagram of
stationary solutions the threshold of the instability signals a bifurcation to
a new phase of non-axisymmetric configurations. We find explicitly this family
of solutions and represent them in the phase diagram. We discuss the
implications of our results for the gravitational system. Rotating
non-axisymmetric black holes necessarily radiate gravitational waves. We thus
emphasize that it would be important, albeit possibly out of present reach, to
have a better understanding of the hydrodynamic description of gravitational
waves and of the gravitational interaction between two bodies. We also argue
that it might well be that a non-axisymmetric m-lobed instability is also
present in Myers-Perry black holes for rotations below the recently found
ultraspinning instability.Comment: 1+22 pages, 3 figures. v2: minor corrections and improvements,
matches published versio
Double primary malignancies associated with colon cancer in patients with situs inversus totalis: two case reports
Situs inversus totalis (SIT) is not itself a premalignant condition, however, rare synchronous or metachronous multiple primary malignancies have been reported. Herein we present a case of synchronous transverse and sigmoid colon cancers and a case of metachronous rectosigmoid colon and gastric cancers in patients with SIT
Control and Characterization of Individual Grains and Grain Boundaries in Graphene Grown by Chemical Vapor Deposition
The strong interest in graphene has motivated the scalable production of high
quality graphene and graphene devices. Since large-scale graphene films
synthesized to date are typically polycrystalline, it is important to
characterize and control grain boundaries, generally believed to degrade
graphene quality. Here we study single-crystal graphene grains synthesized by
ambient CVD on polycrystalline Cu, and show how individual boundaries between
coalescing grains affect graphene's electronic properties. The graphene grains
show no definite epitaxial relationship with the Cu substrate, and can cross Cu
grain boundaries. The edges of these grains are found to be predominantly
parallel to zigzag directions. We show that grain boundaries give a significant
Raman "D" peak, impede electrical transport, and induce prominent weak
localization indicative of intervalley scattering in graphene. Finally, we
demonstrate an approach using pre-patterned growth seeds to control graphene
nucleation, opening a route towards scalable fabrication of single-crystal
graphene devices without grain boundaries.Comment: New version with additional data. Accepted by Nature Material
The clinical significance of preoperative plasma fibrinogen level and platelet count in resectable esophageal squamous cell carcinoma
Decreased SGK1 Expression and Function Contributes to Behavioral Deficits Induced by Traumatic Stress
Exposure to extreme stress can trigger the development of major depressive disorder (MDD) as well as post-traumatic stress disorder (PTSD). The molecular mechanisms underlying the structural and functional alterations within corticolimbic brain regions, including the prefrontal cortex (PFC) and amygdala of individuals subjected to traumatic stress, remain unknown. In this study, we show that serum and glucocorticoid regulated kinase 1 (SGK1) expression is down-regulated in the postmortem PFC of PTSD subjects. Furthermore, we demonstrate that inhibition of SGK1 in the rat medial PFC results in helplessness- and anhedonic-like behaviors in rodent models. These behavioral changes are accompanied by abnormal dendritic spine morphology and synaptic dysfunction. Together, the results are consistent with the possibility that altered SGK1 signaling contributes to the behavioral and morphological phenotypes associated with traumatic stress pathophysiology
Hypergammaglobulinemia in the pediatric population as a marker for underlying autoimmune disease: a retrospective cohort study
The dependence of dijet production on photon virtuality in ep collisions at HERA
The dependence of dijet production on the virtuality of the exchanged photon,
Q^2, has been studied by measuring dijet cross sections in the range 0 < Q^2 <
2000 GeV^2 with the ZEUS detector at HERA using an integrated luminosity of
38.6 pb^-1.
Dijet cross sections were measured for jets with transverse energy E_T^jet >
7.5 and 6.5 GeV and pseudorapidities in the photon-proton centre-of-mass frame
in the range -3 < eta^jet <0. The variable xg^obs, a measure of the photon
momentum entering the hard process, was used to enhance the sensitivity of the
measurement to the photon structure. The Q^2 dependence of the ratio of low- to
high-xg^obs events was measured.
Next-to-leading-order QCD predictions were found to generally underestimate
the low-xg^obs contribution relative to that at high xg^obs. Monte Carlo models
based on leading-logarithmic parton-showers, using a partonic structure for the
photon which falls smoothly with increasing Q^2, provide a qualitative
description of the data.Comment: 35 pages, 6 eps figures, submitted to Eur.Phys.J.
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